Only buying sd cards direct from the manufacturer

So I bought 3 128GB Samsung cards, two were bought from Amazon, and I made sure direct from Amazon, and one direct from Samsung. One of the cards is older, don't know when I bought it but it was about 6 months before the other two, I got it from Amazon. When I got my Gopro 5 I ordered another 128GB card from Amazon and then got an email from Samsung for $10 off at their online store. I went to their store and noticed all their cards were about $20 more than what they were on Amazon so even with the discount I was paying $10 more but I got one anyway as Amazon didn't have the exact card I wanted.

So, the old one still works but isn't anywhere near the advertised speed, the newer one from Amazon wasn't either and sometimes my Gopro would just stop recording with it. The one I got direct from Samsung was the same as the second one from Amazon but an upgrade from the old one I had and it exceeded the speeds it was advertised for and my Gopro hasn't had a problem with it.

So, the old one is still working, but like I said isn't as fast. The second one from Amazon died finally and I didn't use it nearly as the one I got direct from Samsung as it just didn't' transfer as quickly.

For an extra $20 bucks it is worth it to get a card that is the correct advertised speed and a little more assurance it won't die. I think the first two were either counterfit or Samsung keeps the best stock to sell itself, I don't know but I don't think I'll get memory unless it is direct from the manufacturer. With cards getting so large it isn't like anyone needs 20 cards anymore anyway. 3 was way too many cards at 128GB for a Gopro and two is kinda stretching it but it is nice to have a backup.

Anyone else just by direct for the manufacture when it comes to SD cards?

Thanks for first-hand account of unreliability, I know I'll now be more mindful where to go when choosing.

Related: an interesting read on memory card hacking from which I was shocked to learn that some memory cards are (supposedly) sold even when physically they comprise of a majority of bad sectors https://www.bunniestudios.com/blog/?p=3554

Thanks for first-hand account of unreliability, I know I'll now be more mindful where to go when choosing.

Related: an interesting read on memory card hacking from which I was shocked to learn that some memory cards are (supposedly) sold even when physically they comprise of a majority of bad sectors https://www.bunniestudios.com/blog/?p=3554

I wonder also how you're expecting these cards to perform; the stated speeds are only there as a minimum maximum, which is usually the minimum speed when preforming sequential reads. Reading files from them might be split across multiple chunks, so can be expected to be somewhat slower, and especially writing to them can be a lot slower, and most manufacturers just don't quote any kind of write speed.

I wonder also how you're expecting these cards to perform; the stated speeds are only there as a minimum maximum, which is usually the minimum speed when preforming sequential reads. Reading files from them might be split across multiple chunks, so can be expected to be somewhat slower, and especially writing to them can be a lot slower, and most manufacturers just don't quote any kind of write speed.

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Eh, all I know is the second one I bought from Amazon and the one I bought from Samsung are both the same card but when transferring the videos to my computer the one from Amazon was under the speed and the one from Samsung is above the rated transfer rate. I use Linux and as far as I know there isn't a SD speed testing program, I'm just going off of the speed when transfering to my computer which is all I really care about. I guess it is a real life scenario I'm concerned with.

On linux, you can use dd to do sequential reads quite easily. Something like this will read the first 1MB of data from a drive:

Code:

dd if=/dev/sdc of=/dev/null bs=1k count=1000

That, if it's not clear from the command line as is, reads 1000 counts of 1KB of data and dumps it to null. You might get slightly different speeds with different block sizes, but in my experience it doesn't vary that much so 1000 lots of 1KB seems reasonable to me. You'll need to modify the if= argument to point to your real sd card slot which might be sd* or might be mmcblk format under /dev. You can also specify a specific partition to read from if you'd like; it should have little to no difference if the card is genuine.